The inner lives of red giants

摘要

Just as in Hollywood, the age of a star is not always obvious if you look only at the surface. During certain phases in a stars life, its size and brightness are remarkably constant, even while profound transformations are taking place deep inside. For most of their existence, stars shine from the energy released by nuclear reactions that convert hydrogen into helium, but eventually they begin to burn the helium in their cores to synthesize heavier elements, such as carbon and oxygen. On page 608 of this issue, Bedding et al.~1 demonstrate a new technique for distinguishing between these life stages, using continuous 'starquakes' to probe the deepest regions, where the changes are most dramatic.